Lubricating fast setting epoxy composition

ABSTRACT

A composition for a lubricating fast-setting epoxy compound comprising substantially equal amounts of an epoxy base and an epoxy accelerator. The epoxy base comprises: a first micro-crystalline filler, a first talc, a hardenable epoxide containing liquid; and a titanium oxide. The epoxy base can also include a flatting agent. The epoxy accelerator comprises: a second micro-crystalline filler, a second talc, a methylamino accelerator, and a hydrocarbon resin. The epoxy accelerator can also include a modified aliphatic amine, an acrylic resin, a coloring agent, or combinations thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of and claims priority under 35 U.S.C. §120 to U.S. Ser. No. 11/760,567, filed Jun. 8, 2007 which is a continuation-in-part application that claims the benefit, under 35 USC §120, of the prior non-provisional applications having Ser. No. 11/612,376, filed Dec. 18, 2006, Ser. No. 11/612,362, filed Dec. 18, 2006, and Ser. No. 11/612,349, filed Dec. 18, 2006. The prior co-pending non-provisional applications are incorporated by reference along with their appendices.

FIELD

The present embodiments relate to a composition for a lubricating fast-setting epoxy compound.

BACKGROUND

A need exists for a fast-setting epoxy compound capable of curing rapidly, in as little two to twelve minutes, to allow the use of coated materials, such as subsea pipe joints, very soon after application rather than waiting hours for conventional epoxy to cure.

A further need exists for a fast-setting epoxy compound capable of lubricating surfaces, such as surfaces of steel pipes, to enable connections and interference fits without galling or bending the material, then curing rapidly to avoid separation of connected materials.

A need also exists for a fast-setting epoxy compound that is resistant to blushing and bubbling, to allow for even and smooth application to surfaces.

An additional need exists for a fast-setting epoxy compound that cures rapidly at ambient temperatures and high humidity, and is therefore ideal for marine and subsea use.

The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will be understood from the following description, the appended claims and the accompanying drawings, in which:

FIG. 1 depicts an exploded view of a subsea mechanical joint; and

FIG. 2 depicts an alternative embodiment of the pin end with an inverted bevel; and

FIG. 3 depicts a side elevation view of the assembled subsea piping system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before explaining the present embodiments in detail, it is to be understood that the embodiments are not limited to the particular embodiments and that they can be practiced or carried out in various ways.

One advantage of the present composition is that the present composition for a fast-setting epoxy compound creates an epoxy compound that can provide lubrication to surfaces, especially metal surfaces, such as those of steel pipes. Through suspension of one or more micro-crystalline fillers, such as graphite and silica, in the composition, high lubricity is achieved, while the micro-crystalline fillers simultaneously fill porous surfaces such as those of steel pipes.

An additional advantage of the present composition for a fast-setting epoxy compound is that the epoxy compound can cure in as little as two to twelve minutes. Conventional epoxies can require multiple hours to fully cure. The fast-curing nature of the present composition allows connections formed using lubricated surfaces, such as interference fits in metal pipe joints, to be assembled and used rapidly. An interference fit or a similar connection can become disassembled during use if the lubricating compound used to form the connection has not yet fully cured.

A further advantage of the present composition is provided through the use of a suspended micro-crystalline filler in the fast-setting epoxy compound. A micro-crystalline filler provides superior lubricity to the compound, while simultaneously filling porous surfaces, such as those of steel, which further enhances lubricity. Conventional epoxy compositions do not combine a suspended micro-crystalline filler with a fast curing time.

Still another advantage of the present composition is the ability of the fast-setting epoxy compound to cure at ambient temperatures in high humidity. Conventional epoxies often do not cure, or cure more slowly in the presence of moisture or in very high or low ambient temperatures. The present composition is extremely resistant to moisture and blushing. Additionally, the present composition's resistance to moisture helps to inhibit bubbling, allowing the fast-setting epoxy compound to be applied smoothly and evenly to surfaces.

The present composition for a fast-setting epoxy compound is formed by mixing substantially equal amounts of an epoxy base with an epoxy accelerator.

The epoxy base contains a first micro-crystalline filler, a first talc, a hardenable epoxide containing liquid, and a titanium oxide. The epoxy base can also include a flatting agent.

The first micro-crystalline filler of the epoxy base can be crystalline silica, sodium silica, crystalline cellulose, amorphous silica, clay, calcium carbonate, graphite, carbon black, powdered copper, powdered aluminum, powdered barite, fumed silica, fused silica, and combinations thereof.

A preferable first micro-crystalline filler is a mixture of crystalline silica and graphite, due to the added lubricity provided by graphite, as well as the ability of graphite to act as a filler for porous surfaces, such as steel. However, other micro-crystalline fillers can also provide lubricity and fill porous surfaces.

It is contemplated that the first micro-crystalline filler can comprise from about 0.01 to about 35 percent of the epoxy base by weight, with a preferred weight percent of 24%.

The first talc, present in the epoxy base, is contemplated to be magnesium silica, and can be a platy talc. Although talc is hydrophobic, it disperses easily in both aqueous and solvent borne coatings. Due to its shape, talc has a beneficial effect on rheology and contributes to improved brushability, leveling, and sag resistance. Talc is also generally self-suspending in epoxy vehicles and assists in keeping other pigments suspended. Further, talc is readily redispersed.

Talc improves the toughness and durability of the fast-setting epoxy compound. Talc plates can align with the flow of an epoxy coating to be parallel to the substrate after the epoxy cures, creating a physical barrier to the transmission of moisture, thereby improving water and humidity resistance. The reinforcement provided by platy talc can improve the resistance of the cured epoxy to cracking or rupture due to stretching and flexing, thus better insulating the epoxy from the environment.

The barrier properties, alkaline pH, and reinforcement provided by talc contributes to inhibition of corrosion. Micronized talcs, such as 6 Hegman and finer, can be used for titanium dioxide extension, provide good low angle sheen, and good burnishing resistance. Macrocrystalline talcs can also be used as a flatting agent.

It is contemplated that the first talc can comprise from about 0.5 to about 25 percent of the epoxy base by weight, with a preferred weight percent of 18%.

The hardenable epoxide containing liquid of the epoxy base is used as an epoxy resin and can be selected from the group commonly known as bisphenol A (epichlorohydrin). The hardenable epoxide containing liquid can include a diglycidyl ether of 1,4-butanediol, a diglycidyl ether of neopentylglycol, a diglycidyl ether of cyclohexane dimethanol, and combinations thereof.

It is contemplated that the hardenable epoxide containing liquid can comprise from about 50 to about 90 percent of the epoxy base by weight, with a preferred weight percent of approximately 54%.

Titanium oxide, present in the epoxy base, can be a titanium dioxide, a titanium trioxide, or combinations thereof, preferably titanium dioxide. Titanium dioxide can be obtained from Huntsman Tioxide under the trade names of TR60 and TR93. Titanium dioxide can be used both as a dispersion agent and a pigment.

It is contemplated that titanium dioxide can comprise from about 0.01 to about 15 percent of the epoxy base by weight, with a preferred weight percent of 4%.

If the epoxy base includes a flatting agent, the flatting agent can be titanium dioxide, magnesium silica, zinc, amorphous silica, or combinations thereof. A preferred flatting agent is zinc, due to zinc's added function as an anti-corrosive agent.

It is contemplated that the flatting agent can comprise from about 0.001 to about 10 percent of the epoxy base by weight, with a preferred weight percent of 1%.

The epoxy accelerator contains a second micro-crystalline filler, a second talc, a methylamino accelerator, and a hydrocarbon resin. The epoxy accelerator can also include a modified aliphatic amine, an acrylic resin, a coloring agent, or combinations thereof.

The second micro-crystalline filler, present in the epoxy accelerator can be crystalline silica, sodium silica, crystalline cellulose, amorphous silica, clay, calcium carbonate, graphite, carbon black, powdered copper, powdered aluminum, powdered barite, fumed silica, fused silica, and combinations thereof.

A preferred second micro-crystalline filler can be crystalline silica. Crystalline silica is a thixotropic additive which, when dispersed, increases viscosity, imparts thixotropic behavior, and adds anti-sag and anti-setting characteristics. Crystalline silica can be obtained from the Degussas Corporation under the trade name Aerosil 300.

Synthetic fused silica is an alternative preferred second micro-crystalline filler. Synthetic fused silica is made from a silica-rich chemical precursor, resulting in a transparent amorphous solid with an ultra-high purity and excellent optical transmission.

It is contemplated that the second micro-crystalline filler can comprise from about 20 to about 50 percent of the epoxy accelerator by weight, with a preferred weight percent of 33%.

The second talc, present in the epoxy accelerator, is contemplated to be magnesium silica, and can be a platy talc, a micronized talc, such as 6 Hegman or finer, a macrocrystalline talc, or anther talc. The second talc can be the same type of talc as the first talc, or a different kind of talc.

It is contemplated that the second talc can comprise from 10 to 30 percent of the epoxy accelerator by weight, with a preferred weight percent of 16%.

The methylamino accelerator of the epoxy accelerator can be a dimethylamino accelerator, a trimethylamino accelerator, or similar accelerators. The first methylamino accelerator can be dimethylaminoethanol, dimethylethanolamine, n,n,-dimethylaminoethanol, 2-(dimethylamino)ethanol, N,N,-dimethyl-2-hydroxyethylamine, triethanolamine, piperazine, n-aminoethylpiperazine, 2-4-6 Tri(dimethylaminomethyl)phenol, and combinations thereof.

A preferred methylamino accelerator is 2-4-6 Tri(dimethylanimomethyl)phenol.

It is contemplated that the methylamino accelerator can comprise from about 0.01 to about 60 percent of the epoxy accelerator by weight, with a preferred weight percent of 45%.

The hydrocarbon resin of the epoxy accelerator can be a polyalphamethylstyrene, such as those obtainable from the Aldrich Chemical Company.

Polyalphamethylstyrenes undergo specific chain scission with breakage occurring only at its ends. Polyalphamethylstyrenes depolymerize to become the constituent monomer present in the epoxy accelerator.

It is contemplated that the hydrocarbon resin can comprise from 0.001 to 15 percent of the epoxy base by weight, with a preferred weight percent of approximately 5%.

If the epoxy accelerator includes a modified aliphatic amine, the modified aliphatic amine can be an aliphatic polyaminoaminde. Aliphatic polyaminoamides are room temperature reacting curing agents derived from aliphatic amines that have been modified to reduce their vapor pressure, thereby reducing their corrosiveness. The modifications optimize the hardness, reactivity, handling time, and carbonation resistance of the aliphatic amines.

Aliphatic polyaminoamindes exhibit high reactivity, low viscosity, and excellent resistance to organic acids and solvents with good adhesion to concrete and steel. Aliphatic polyaminoamides are available from Air Products under the Tradename of Anacamine 2423.

The aliphatic polyaminoamide can be a cycloaliphatic amine which can provide improved resistance to aqueous solutions, solvents, and mineral acids comparable to an aromatic amine cured composition. Cycloaliphatic curing agents provide good color stability, superior resistance to carbamation, superior chemical resistance, and good water spotting and amine blush properties.

Aliphatic polyaminoamides are preferred due to exhibiting a rapid cure time at room temperature in the presence of humidity. Aliphatic polyaminoamides can be used to cure the fast-setting epoxy composition by reacting with epoxide groups or promoting self-polymerization of the epoxy by catalytic action.

It is contemplated that the modified aliphatic amine can comprise from about 20 to about 50 percent of the epoxy accelerator by weight, with a preferred weight percent of 35%.

If the epoxy accelerator includes an acrylic resin, the acrylic resin is contemplated to be a glassy thermoplastic, which can be used in coating, adhesives, and numerous thermoplastic or thermosetting polymers or copolymers of acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile, used to produce paints, synthetic rubbers, and lightweight plastics.

The acrylic resin can comprise from about 0.001 to about 10 percent of the epoxy accelerator by weight, with a preferred weight percent of 0.85%.

If the epoxy accelerator includes a coloring agent, the coloring agent can be a phthalocyanine, though use of other coloring agents is also contemplated.

The phthalocyanine can be a metal phthalocyanine, such as copper phthalocyanine, gold phthalocyanine, titanium phthalocyanine, cobalt phthalocyanine, and combinations thereof. A dispersion of copper phthalocyanine is preferred. Copper phthalocyanine is a phthalo blue or green dispersion, which can be used as a pigment. Copper phthalocyanine is advantageous because it does not cause flocculation, which is the aggregation or grouping together of pigment particles, causing a reduction in pigment tinting power. Copper phthalocyanine exhibits a clean tint and good light qualities.

It is contemplated that the coloring agent can comprise from about 0.001 to about 10 percent of the epoxy accelerator by weight, with a preferred weight percent of 1%.

In a preferred embodiment, the epoxy base can include the following:

Bisphenol A 54% by weight Crystalline Silica 24% by weight Magnesium Silica (Talc) 18% by weight Titanium Dioxide  4% by weight and the epoxy accelerator can include the following:

2-4-6 Tri(dimethyl aminomethyl) Phenol 45% by weight Crystalline Silica 33% by weight Magnesium Silica (Talc) 16% by weight Polyalphamethylstyrene  5% by weight Green Color  1% by weight

In an alternative preferred embodiment, the epoxy accelerator can include the following:

Aliphatic Polyaminoamide   35% by weight Crystalline Silica   30% by weight Magnesium Silica (Talc)   21% by weight 2-4-6 Tri(dimethyl aminomethyl) Phenol 8.15% by weight Polyalphamethylstyrene   4% by weight Phthalo Blue Color   1% by weight Acrylic Resin 0.85% by weight

An embodiment of the present composition for a fast-setting epoxy compound can be produced by the following method:

The first micro-crystalline filler, the first talc, and the titanium oxide can be mixed into the hardenable epoxide containing liquid to form the epoxy base. The mixing can be done in a special vacuum tank having impellers and performed under vacuum dispersion. A flatting agent can also be mixed into the hardenable epoxide containing liquid.

The vacuum on the vacuum tank can be started before starting the impellers are started, thereby evacuating air before the mixing causes any air entrapment. After high vacuum is achieved, both impellers can be started, thus providing rapid dispersion with no air entrapment.

The impellers can be started at a low speed and gradually increased slowly to increase circulation. The impellers can be increased the to maximum dispersing speed while staying within the limitation of the impeller motor amperage rating. The speeds of both impeller shafts can be charged simultaneously and adjusted slowly to reach the optimum point of flow and dispersion without creating cavitations in the epoxy base.

If the mixing creates a temperature approaching or exceeding 160 degrees centigrade, which can denature the ingredients, the mixing can be slowed or stopped to reduce the temperature. After the epoxy base has reached a satisfactory degree of dispersion, both impellers can continue mixing until a homogenous state is reached. After the homogenous state is reached, the vacuum tanks can be sealed to prevent air from contacting the epoxy base until it is to be mixed with the epoxy accelerator.

The second micro-crystalline filler, the second talc, and the hydrocarbon resin can be mixed to form an accelerator mixture. The accelerator mixture can be mixed using the same procedure by which the epoxy base was mixed. A modified aliphatic amine, an acrylic resin, a coloring agent, or combinations thereof can also be mixed into the accelerator mixture.

The methylamino accelerator can then be mixed into the accelerator mixture forming the epoxy accelerator, which can also be sealed to prevent contact with air until the epoxy accelerator is to be mixed with the epoxy base.

When ready for use, substantially equal amounts of the epoxy base and the epoxy accelerator can be mixed, forming a lubricating fast-setting epoxy compound having a high lubricity, sufficient to press two segments of steel pipe in an interference fit using a hydraulic press without damaging the pipe segments or galling the metal. The lubricating fast-setting epoxy compound further has a curing time ranging from two to twelve minutes, allowing sufficient time for the compound to be applied to lubricate a surface and utilized, then curing very shortly thereafter.

The mixing can be done using a banbury mixer, a high shear mixer, a dispersion machine, a stone mill, a ball mill, a roller mill, a vacuum tank having at least one impeller, or combinations thereof. In a preferred embodiment, a vacuum tank operably connected to a dispersion machine having a low speed impeller and a high speed impeller is used.

The mixing can be done using constant agitation, variable agitation, intermittent agitation, gradually increasing agitation, or combinations thereof.

It is contemplated that the epoxy base, the accelerator mixture, the epoxy accelerator, or combinations thereof can be heated during mixing, to a temperature ranging from about 10 degrees centigrade to about 160 degrees centigrade, to promote homogeneity. The mixing can be slowed or stopped to prevent the temperature from exceeding 160 degrees centigrade.

The mixing speed can be adjusted as needed to promote or maintain homogeneity and produce small amounts of heat as needed. The temperature can also be adjusted as needed to promote homogeneity.

The subsea mechanical joint includes a first tubular member having a bell end. The bell end includes a central axis and an interior sized to form an interference fit with a pin end of a second tubular member. The tubular member can be a schedule 40 pipe.

The second tubular member has a pin end, an exterior, including the pin end and the second tubular body, a tapered portion disposed between a pin end and a second tubular body, a central axis, and can include an annular groove formed within the second tubular body.

The present embodiment of the subsea mechanical joint can also include a liquid fast setting epoxy compound, such as a mixture of 85% epoxy resin and 15% inert ingredients for friction reduction, as a lubricant, and for pigmentation for use in assembling the tubulars. The fast setting epoxy compound can be applied to the interior of the bell end and the exterior of the pin end sequentially. The fast setting epoxy compound should fill the annular groove and the tapered portion of the pin end.

The interference fit should not generate a gripping force between the bell end and pin end that would cause the pin end to experience a stress greater than the elastic limit for each material used.

The embodiments of the invention save the environment by joining tubular members together with predictable mechanical joints that do not burst or leak when properly applied. When tubular members are welded together, the joints are sometimes unpredictable, which can result in the joint between the tubular members failing, causing the material transported within the pipes to leak or flow into the open environment. The transportation of oil in pipelines particularly requires that the tubular members making up the pipeline are joined together in a predictable manner, especially as the world's energy needs expand, increasing the need to retrieve or pipe oil from remote environmentally pristine areas. The present invention provides these benefits.

Another benefit of the subsea mechanical joint is that it can be used to join tubular members made of steel, which have different levels of hardness. The invention can also be used to join soft materials, such as aluminum.

The subsea mechanical joint can be better understood with reference to the Figures. Referring now to FIG. 1, which depicts an exploded view of the subsea mechanical joint.

FIG. 1 depicts a first tubular member 2, and second tubular member 12 having a pin end 10. The first tubular member 2 has a first tubular body 35. The first tubular member 2 has a bell end 4 disposed on the first tubular body 35. The bell end 4 can include a central axis 6. The bell end has an interior 8, and a fast setting epoxy compound disposed on the interior.

A second tubular member 12 is also depicted. The second tubular member 12 has a pin end 10 selectively which has a central axis 20 with a tapered portion 16 disposed between the pin end 10 and a second tubular body 18. Additionally, a fast setting epoxy compound is disposed on the pin end 10.

Also shown is a exterior 14 which is an exterior for the pin end 10 and the tubular body 18, with an annular groove 22 and a depth insertion mark 32.

The tapered portion 16 can have an angle ranging from 0.5 degrees to 10 degrees, such as 3 degrees, relative to the central axis 20. The tapered portion 16 decreases in size in a small amount depending on the size of the pipe. The tapering occurs over about ½ inch of the length of the second tubular member 12, just at the end of the second tubular member 12.

The fast setting epoxy compound reduces galling of the bell end 4, which is located on the first tubular member 2, when the pin end 10 is inserted into the bell end 4.

The fast setting epoxy compound is disposed on the exterior 14 of the second tubular body on the pin end 10 and the interior 8 of the bell end 4 of the first tubular member 2.

The fast setting epoxy completely fills an annular groove 22 on the second tubular body 18 as well the adjacent area 30 located between the tapered end 16 and the annular groove 22.

The annular groove 22 is formed in an embodiment, by a hydraulic groover or machined into the pipe. The hydraulic groover is better than machining because no metal is removed from the pipe and no sharp edges are left on the pipe.

The annular groove 22 ensures a strong subsea mechanical joint because the groove acts as a reservoir to ensure that there is adequate fast setting epoxy compound to cover the entire end of the pipe.

The annular groove preferably has a depth ranging from 0.015 inches to 0.035 inches and a width ranging from 0.05 inches to 0.07 inches. In an embodiment, the annular groove can be located between ½ and 1 inch from the end of the pin end 10.

The subsea mechanical joint as disclosed allows for the fast setting epoxy to be applied to prevent damage to the tubular during the stabbing process of the pin end 10 into the bell end 4.

Particularly, the bell end 4 has a slight first outward flare 39 a disposed between the bell end 4 and a first face 38 a, which is above the central axis 6, and a second outward flare 39 b disposed between the bell end 4 and a second face 38 b, which is below the central axis 6. The first outward flare forms a outward flare angle 120 relative to the central axis 6. The second outward flare forms a substantially similar angle.

The tapered portion 16 has a small inward taper angle 110 relative to the central axis 20. The outward flare angle 120 can be any angle less than the tapered angle. Good results have been experienced when a joint was made using a tapered end having an angle of 3 degrees and a flare on the bell end of 4 degrees for a joint on 6 inch diameter pipe wherein the stabbed in, overlapping portion of the joint an overall length between 7 and 10 inches, about 9.5 inches.

The fast setting epoxy compound allows the subsea joint to be quickly submergible into deep water of a depth ranging from approximately 300 feet to 1000 feet after the tubular ends have been joined because of this coating. The setting time, the curing time of the coating on the pipe can occur in a relatively short period usually ranging from in as little as 8 seconds or as much as 25 seconds. Because the cure time is very short, the pipe can be quickly submerged, whereas it takes several hours with traditional, slower setting compounds. The portion of the tubular body not covered should start approximately 0.5 inches past a depth insertion mark 32 on the side of the depth insertion mark closest to the annular groove 22 and extend to the end of the pin end 10.

Additionally in FIG. 1, the depth insertion mark 32 is shown, which indicates how far the pin end 10 should be stabbed into the bell end 4.

FIG. 2 depicts an alternative embodiment of the pin end 10.

In this FIG. 2, the pin end 10 has a central axis 20; a tapered portion 16; the second tubular body 18; a fast setting epoxy compound, such as a mixture of 85% epoxy resin and 15% inert ingredients for friction reduction and pigmentation. Additionally, FIG. 2 shows an inverted bevel 36. The inverted bevel 36 is a tapered edge where the inside shoulder of the pin end has been removed. The inverted bevel is used to improve the geometry of the inside of the pipe joint. Also shown in the FIG. 2 is the exterior 14, the annular groove 22, and the depth insertion mark 32.

The inverted bevel 36 is prefabricated by a steel manufacturer of the entire tubular member. The inverted bevel does not have to done in prefabrication and can be done by another party, after the pipe has been created by the pipe manufacturer. The inverted bevel 36 has the benefit of improving the hydraulic efficiency through the joint.

The advantage of the interference fit is to provide a fit that prevents leaking. No threading or welding is needed when this interference fit is made. Force is used to create the interference fit, such as a hydraulic press. This type of sealing engagement insures a tight, leak proof seal. The interference fit process is faster than other types of pipe joining. Additionally, by using interference fits, there is no need to perform x-rays to detect cracks or hairline fractures in a weld because no weld is made.

It is contemplated that the pin end 10 can have an insertion depth of between 5 inches to 14 inches into the bell end 4 depending on the size, the diameter of the pipe.

In this alternative embodiment of the subsea mechanical joint, the tapered end 16 can have an angle ranging from 0.5 degrees to 16 degrees.

In yet another alternative embodiment of the subsea mechanical joint, it is further contemplated that the bell end 4 can have an inner diameter of not less than the outer diameter of the pin end 10 less the product of 0.005 times the outer diameter of the second tubular member 12.

For example, but without limitation, a “minimum interference fit” for steel has been determined to be approximately 0.005 inches of outside diameter per 30,000 pounds per square inch of minimum specified yield.

An embodiment contemplates using 0.003 inch, but 0.005 was used to compensate for miscellaneous irregularities which may be found in the tubular member.

For example, for a nominal 4.5 inch diameter pipe, the standards on such pipe allow a tolerance of plus or minus 0.75%. A 4.5 inch diameter pipe with A.P.I. standards may thus be encountered with an outside diameter as small as 4.46625 inches. Thus, to allow for the minimum desired interference of 0.0225 inches, the bell end must be expanded such that its dimension after “snap-back” is approximately 4.44 inches. Such sizing to obtain a “minimum interference fits has been found to satisfactorily accommodate pin ends of pipe with a maximum positive A.P.I. variation without significantly increasing the force required for joining, and while maintaining an adequate gripping force.

The relationship described above may be expressed as follows:

a. B.D.=Min. O.D. pin−0.005X, where

b. B.D.=bell inner diameter in inches;

c. Min O.D pin=smallest pin end outer diameter;

d. X=Nominal second tubular member outer diameter.

The invention also relates to a method for forming a subsea mechanical joint.

An embodiment of the method for forming a subsea mechanical joint can include forming a bell end in the end portion of a first tubular member. The bell end can receive a pin end of a second tubular member.

An embodiment of the method can include yielding the end portion of the first tubular member forming the bell end sized to receive the pin end of the second tubular member with an interference fit.

The yielding of the end portion of the first tubular member can be accomplished by using a hydraulic press, which exerts a pressure between the mandrel and end of the pipe. The hydraulic press exerts a force ranging from 10 to 50 tons, forcing the mandrel into the end portion of the first tubular member, causing it to yield. The mandrel is sized according to the tubular member that is used. The mandrel is made of hardened steel.

The present embodiment of the method can further include deforming the end portion of the second tubular member, which forms the pin end. The pin end can have a tapered portion.

The deforming operation can be accomplished by using a roll forming machine. The roll forming machine can have rollers. The rollers control the angle of the tapered portion of the pin end.

The present embodiment can also include forming an annular groove. The annular groove is formed by a ridge on the roller. The annular groove can be located on the exterior of a tubular body. The annular groove should be located as proximate to the tapered portion as practicable.

It is contemplated that the annular groove can be disposed within the bell end when the interference fit is made.

The present embodiment of the method further includes applying a fast setting epoxy compound, such as a mixture of 85% epoxy resin and 15% inert ingredients for friction reduction and pigmentation, to the interior of the bell end and the exterior of the pin end.

The fast setting epoxy compound can be a compound having a fast curing time. The fast setting epoxy compound can be mixed using a machine that meters and mixes the fast setting epoxy compound and delivers it to a nozzle for the application of the fast setting epoxy compound to the tubular member by hand.

The fast setting epoxy compound should be applied so that when the interference fit is made, the fast setting epoxy compound fills the annular groove and an adjacent annular space between the tapered portion and the annular groove. The fast setting epoxy compound can be set in a span of time ranging from 1 minute to 10 minutes.

The present embodiment of the method also includes inserting the pin end into the bell end, creating the interference fit. The pin end is inserted into the bell end by using a hydraulic press.

When in the interference fit, the bell end exerts a compressive force on the pin end. The compressive force is usually less than the yield strength of the pin end. The pressure exerted on the pin end forms the subsea mechanical joint between the first tubular member and the second tubular member. The subsea mechanical joint is capable of withstanding a pressure equal to that of the first tubular member and second tubular member.

In another alternative embodiment of the method further includes deforming the pin end and bell end relative to each other. This ensures that when the pin end and bell end are interfitted, they will have a minimum interference fit there between.

During the yielding of the end portion of the first tubular member, the bell end is strain hardened, which increases the yield strength of the end portion by up to about 10 percent.

It is also contemplated that the method can include applying a depth insertion mark to the second tubular body during coating. The insertion depth can be controlled by using the hydraulic press and stopping the hydraulic press when the depth insertion mark is perpendicular with the first face and second face of the bell end.

It is contemplated that the fast setting epoxy can set within a span of time ranging from 1 minute to 10 minutes.

It is also contemplated that the deforming of the pin end can be accomplished by using a roll forming machine. The roll forming machine can have a set of rollers with pitch angles varying from 0.5 degrees to 10 degrees depending on whether the pipe is internally coated or not.

The embodiments of the invention generally relate to a subsea piping system. The subsea piping system can have a first tubular member.

The first tubular member can have a first tubular body. The first tubular body can have a first pin end and a first bell end opposite the first pin end.

The embodiments of the subsea piping system can have a second tubular member with a second tubular body. The second tubular body can have a second pin end and a second bell end opposite the second pin end.

The embodiments of the subsea piping system can have a third tubular member with a third tubular body comprising at least a third pin end.

The embodiments of the piping system can have a fourth tubular member with a fourth tubular body having at least a third bell end.

The first bell end has a first interior sized to form a first interference fit with the second pin end. The second tubular member has a second exterior, a second tapered portion formed between the second tubular body and the second pin end, and a second annular groove formed within the second tubular body.

The third bell end can have an interior sized to form a second interference fit with the first pin end. The first tubular has a first pin end, a first exterior, a first tapered portion formed between the first tubular body and the first pin end, and a first annular groove formed within the first tubular body.

The first end of the fourth tubular member opposite the third bell end can be a connection to a supply source, such as a subsea wellhead.

The second bell end of the second tubular member comprises a second interior sized to form a third interference fit with the third pin end.

The third pin end has a third exterior, a third tapered portion formed between the third tubular body and a third tubular body, and a third annular groove (not shown) formed within the third tubular body of the third pin end.

The third tubular member can have the smooth fusion powder epoxy coating disposed on a third portion of the third tubular body.

The fast setting epoxy compound is applied to the second interior of the second bell end and the third exterior of the third pin end, wherein the fast setting epoxy compound fills the third annular groove and a third adjacent space between the third annular groove and the third tapered portion.

The second end of the third tubular member opposite the third pin end can have a connection to a receiving source, such as a storage tank.

The first tubular body, second tubular body, and third tubular body comprise a first depth insertion mark, a second depth insertion mark, and a third depth insertion mark respectively.

The first portion can be from a first space between the first tapered portion and first depth insertion mark to the first bell end. The second portion can be a second space between the second tapered portion and the second depth insertion mark to the second bell end. A third portion comprises can be a third space between the third tapered portion and the third depth insertion mark to the connection to the receiving source.

The first space is between 0.01 inches to a 0.5 inches past the first depth insertion mark towards the first annular groove. The second space is between 0.01 inches to 0.5 inches past the second depth insertion mark towards the second annular groove. The third space is 0.01 inches to 0.5 inches past the third depth insertion mark towards the third annular groove. The portion of the pin end and the associated tubular that is going to be in contact with an interior of a bell end should not have a coating on it such as the smooth fusion powder epoxy coating or the three layer polyethylene coating.

In another embodiment of the subsea piping system can have the first tubular body having the first depth insertion mark disposed on the first tubular body allowing the first pin end to comprises a depth of insertion from 3 inches to 15 inches into the third bell end. The second tubular body further comprises the second depth insertion mark disposed on the first tubular body allowing the second pin end to comprises a depth of insertion from 3 inches to 15 inches into the first bell end. The third tubular body further comprises the third depth insertion mark disposed on the third tubular body allowing the third pin end to comprise a depth of insertion from 3 inches to 15 inches into the second bell end.

In another embodiment of the subsea piping system the first pin end, the second pin end, and the third pin end can also have an inverted bevel disposed on the tapered portion. The inverted bevel can be prefabricated by a steel manufacturer of the entire tubular member. The inverted bevel does not have to done in prefabrication and can be done by another party, after the pipe has been created by the pipe manufacturer. The inverted bevel has the benefit of improving the hydraulic efficiency through the joint.

The tubular members can be schedule 40 pipe. Other pipes, from as low as schedule 5 pipe to a maximum of schedule 80 pipe and even tip to 160 pipe can be used.

The interference fits formed when the pin ends interact with the bell end should not generate a gripping force between the bell ends and pin ends that would cause the pin ends to experience a stress greater than the elastic limit for each material used.

FIG. 3 depicts an assembled cut view of the piping system. The fourth tubular member 414 is shown operatively connected to a supply source 410 at one end. Tubular member 414 is shown operatively connected and at an opposite end in a third interference fit with the first tubular member 2. The third interference fit is formed when the first pin end 26 is disposed within the third bell end 408.

The first tubular member 2 is shown in a first interference fit with the second tubular member 12 (See FIG. 1). The first interference fit between the first tubular member 2 and the second tubular member 12 is operatively formed when the bell end 4 operatively has the second pin end 10 disposed within it.

A second interference fit is operatively formed between the second tubular member 2 and the third tubular member 402. The second interference fit is formed when the third pin end 406 is operatively disposed within the second bell end 15. The end of the third tubular member 402 opposite the pin end 406 is operatively connected to a receiving source 404.

The piping system relates to a method for forming the joints that couple the tubular members together.

While these embodiments have been described with emphasis on the embodiments, it should be understood that within the scope of the appended claims, the embodiments might be practiced other than as specifically described herein. 

1. A subsea mechanical joint, comprising: a first tubular member having a bell end and a second tubular member having a pin end, an interior of the bell end being sized to form an interference fit with the pin end of the second tubular member; and a lubricating fast-setting epoxy composition applied to an interior of the bell end and an exterior of the pin end and comprising substantially equal amounts of an epoxy base and an epoxy accelerator, the composition being formed by a process comprising: (a) forming the epoxy base by mixing under vacuum dispersion into a hardenable epoxide containing liquid: a first micro-crystalline filler; a first talc; and a titanium oxide; and (b) forming the epoxy accelerator by mixing under vacuum dispersion: a second micro-crystalline filler; a second talc; a methyloamino accelerator; and a hydrocarbon resin; and (c) mixing the epoxy base with the epoxy accelerator; wherein the epoxy composition is capable of complete curing within two to twelve minutes.
 2. The subsea mechanical joint of claim 1, wherein the epoxy base in (a) further comprises a flatting agent.
 3. The subsea mechanical joint of claim 1, wherein the epoxy accelerator in (b) further comprises a modified aliphatic amine, an acrylic resin, a coloring agent, or combinations thereof.
 4. The subsea mechanical joint, wherein the first micro-crystalline filler is selected from the group consisting of: crystalline silica, sodium silica, crystalline cellulose, amorphous silica, clay, calcium carbonate, graphite, carbon black, powdered copper, powdered aluminum, powdered barite, fumed silica, fused silica, and combinations thereof.
 5. The subsea mechanical joint of claim 1, wherein the first talc is a platy talc.
 6. The subsea mechanical joint of claim 1, wherein the hardenable epoxide containing liquid is selected from the group consisting of: an epichlorohydrin, a diglycidyl ether of 1,4-butanediol, a diglycidyl ether of neopentylglycol, a diglycidyl ether of cyclohexane dimethanol, and combinations thereof.
 7. The subsea mechanical joint of claim 1, wherein the titanium oxide is titanium dioxide, titanium trioxide, or combinations thereof.
 8. The subsea mechanical joint of claim 2, wherein the flatting agent is selected from the group consisting of: titanium dioxide, magnesium silica, zinc, amorphous silica, and combinations thereof.
 9. The subsea mechanical joint of claim 1, wherein the second micro-crystalline filler is selected from the group consisting of: crystalline silica, sodium silica, crystalline cellulose, amorphous silica, clay, calcium carbonate, graphite, carbon black, powdered copper, powdered aluminum, powdered barite, fumed silica, fused silica, and combinations thereof.
 10. The subsea mechanical joint of claim 1, wherein the second talc is a platy talc.
 11. The subsea mechanical joint of claim 1, wherein the methylamino accelerator is a dimethylanimo accelerator, a trimethylamino accelerator, or combinations thereof.
 12. The subsea mechanical joint of claim 1, wherein the methylamino-accelerator is selected from the group consisting of: dimethylaminoethanol, dimethylethanolamine, n,n,-dimethylaminoethanol, 2-(dimethylamino) ethanol, N,N,-dimethyl-2-hydroxyethylamine, 2,4,6 Tri(dimethylaminomethyl)phenol, and combinations thereof.
 13. The subsea mechanical joint of claim 1, wherein the hydrocarbon resin is a polyalphamethylstyrene.
 14. The subsea mechanical joint of claim 3, wherein the modified aliphatic amine is an aliphatic polyaminoamide.
 15. The subsea mechanical joint of claim 14, wherein the aliphatic polyaminoamide is a cycloaliphatic amine.
 16. The subsea mechanical joint of claim 3, wherein the acrylic resin is a thermoplastic.
 17. The subsea mechanical joint of claim 3, wherein the coloring agent is a phthalocyanine.
 18. The subsea mechanical joint of claim 17, wherein the phthalocyanine is a metal phthalocyanine.
 19. The subsea mechanical joint of claim 18, wherein the metal phthalocyanine is copper phthalocyanine, gold phthalocyanine, titanium phthalocyanine, cobalt phthalocyanine, or combinations thereof.
 20. The subsea mechanical joint of claim 1, wherein the epoxy base in (a) comprises: 0.01 to 35 weight percent of the first micro-crystalline filler; 0.5 to 25 weight percent of a first talc; 50 to 90 weight percent of the hardenable epoxide containing liquid; and from 0.01 to 15 weight percent of the titanium oxide.
 21. The subsea mechanical joint of claim 2, wherein the epoxy base in (a) comprises from 0.001 to 10 weight percent of the flatting agent.
 22. The subsea mechanical joint of claim 1, wherein the epoxy accelerator comprises: 20 to 50 weight percent of the second micro-crystalline filler; 10 to 30 weight percent of the second talc; 0.01 to 60 weight percent of the methylamino accelerator; and 0.001 to 15 weight percent of the hydrocarbon resin.
 23. The subsea mechanical joint of claim 3, wherein the epoxy accelerator comprises 20 to 50 weight percent of the modified aliphatic amine, 0.001 to 10 weight percent of the acrylic resin, and 0.001 to 10 weight percent of the coloring agent.
 24. A subsea piping system comprising a plurality of interconnected adjoining tubular members, wherein each interconnected adjoining tubular member comprises the subsea mechanical joint of claim
 1. 25. The subsea mechanical joint of claim 1, wherein at least one of the first and second microcrystalline filler comprises graphite.
 26. The subsea piping system of claim 24, wherein at least one of the first and second microcrystalline filler comprises graphite. 